Vibration dampening muffler and system

ABSTRACT

Various methods and systems are provided for damping vibrations at a muffler. In one example, a system comprises an exhaust component, a muffler configured to receive exhaust gas from the exhaust component, and a vibration isolation device coupled between the exhaust component and the muffler, the vibration isolation device comprising a vibration dampening element and an active biasing element.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Patent Application No. 62/033,200, entitled MUFFLER VIBRATION DAMPENING, filed Aug. 5, 2014, which is hereby incorporated in its entirety herein by reference for all purposes.

FIELD

Embodiments of the subject matter disclosed herein relate to a system for an engine exhaust.

BACKGROUND

When exhaust gas is expelled out of an engine, the gas produces noise that may be undesirable to an operator or bystander, and thus exhaust systems typically include a muffler to attenuate the noise produced by the exhaust gas. Mufflers may be exposed to various excitation forces, including engine excitations, high frequency turbo excitations, gas pressure, thermal loads, etc. Due to these excitation forces, mufflers may become degraded, for example, they may experience weld failures. Typical mechanisms for damping vibrations, such as rubber pads fastened to the muffler and/or exhaust component to which the muffler is coupled, are prone to degradation from exposure to high temperature exhaust gases.

BRIEF DESCRIPTION

In one embodiment, a system comprises an exhaust component, a muffler configured to receive exhaust gas from the exhaust component, and a vibration isolation device coupled between the exhaust component and the muffler. The vibration isolation device includes a vibration dampening element and an active biasing element.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood from reading the following description of non-limiting embodiments, with reference to the attached drawings, wherein below:

FIG. 1 shows a schematic diagram of a vehicle with a turbocharger according to an embodiment of the disclosure.

FIG. 2 shows a front view of a muffler coupled to a turbocharger.

FIG. 3 shows a cross-sectional view of the muffler-turbocharger system of FIG. 2.

DETAILED DESCRIPTION

Embodiments of the subject matter disclosed herein relate to a system including a muffler coupled to an exhaust component and a vibration isolation device coupled between the muffler and the exhaust component. The vibration isolation device comprises a vibration dampening element, such as a spring, and an active biasing element, such as a shape-memory alloy wire. The system may be installed in an exhaust system of an engine, and the exhaust component and muffler may each receive a flow of exhaust gas from the engine. In some examples, the exhaust component to which the muffler is coupled may be a turbocharger turbine. In other examples, the muffler may be coupled to an aftertreatment device or directly to the engine. The muffler may include any number or configuration of sound-absorbing, cancellation, or reflection chambers.

The approach described herein may be employed in a variety of engine types, and a variety of engine-driven systems selected with reference to application specific criteria. Some of these systems may be stationary, while others may be on semi-mobile or mobile platforms. Semi-mobile platforms may be relocated between operational periods, such as mounted on flatbed trailers. Mobile platforms include self-propelled vehicles. Such vehicles can include on-road transportation vehicles, as well as mining equipment, marine vessels, rail vehicles, and other off-highway vehicles (OHV). For clarity of illustration, a locomotive may be used as an example of a mobile platform supporting a system incorporating an embodiment of the invention.

Aspects of the invention are disclosed with reference to a vehicle having an engine and exhaust system, such as the vehicle illustrated in FIG. 1. The exhaust system may include a turbocharger having a turbine to receive exhaust gas from the engine and pass the exhaust gas to a muffler. The turbine may be coupled to the muffler via a vibration isolation device that includes at least vibration dampening element surrounding an active biasing element, as illustrated in FIGS. 2-3. The muffler may include an outer liner surrounding an inner liner, and may further include one or more active biasing elements coupled between the inner and outer liners, as illustrated in FIG. 3.

Before further discussion of the vibration isolation embodiments, a positioning of a turbocharger in an engine system is shown. FIG. 1 shows a block diagram of an embodiment of a vehicle system 100 (e.g., a locomotive system), herein depicted as vehicle 106. The illustrated vehicle is a rail vehicle configured to run on a rail 110 via a plurality of wheels 112. As depicted, the vehicle includes an engine system with an engine 104.

The engine receives intake air for combustion from an intake passage 114. The intake may be any suitable conduit or conduits through which gases flow to enter the engine. For example, the intake may include an intake manifold 115, the intake passage, and the like. The intake passage receives ambient air from an air filter (not shown) that filters air from outside of the engine. Exhaust gas resulting from combustion in the engine is supplied to an exhaust, such as exhaust passage 116. The exhaust, or exhaust passage, may be any suitable conduit through which gases flow from the engine. For example, the exhaust may include an exhaust manifold 117, the exhaust passage, and the like. Exhaust gas flows through the exhaust passage and out of the engine system. In one example, the engine is a diesel engine that combusts air and diesel fuel through compression ignition. In other non-limiting embodiments, the engine may combust fuel including gasoline, kerosene, biodiesel, or other petroleum distillates of similar density through compression ignition (and/or spark ignition). In still further examples, the engine may be a dual or multi-fuel engine configured to combust more than one fuel, such as diesel and natural gas.

In one embodiment, the engine is a Vee engine (e.g., V-engine) having a first bank of cylinders and a second bank of cylinders. In one example, the engine is a V-12 engine having twelve cylinders. In other examples, the engine may be a V-6, V-8, V-10, or V-16 or any suitable V-engine configuration. In another embodiment, the engine is an in-line engine including a plurality of cylinders. The engine includes an engine block and an engine head. The engine head includes a plurality of cylinder heads, each cylinder head including a respective cylinder. Each cylinder head includes a valve cover. Additionally, each cylinder head includes a fuel injector. Each fuel injector passes through a respective valve cover and connects to a high pressure fuel line. The high pressure fuel line runs along a length of the engine. Each cylinder head is further coupled to the exhaust manifold. As such, exhaust gases produced during combustion exit the cylinder heads through the exhaust manifold and then flow to the exhaust passage. The exhaust passage contains additional engine system components, including a turbine of a turbocharger 120 and a muffler 210, described further below.

The turbocharger is arranged between the intake passage and the exhaust passage. The turbocharger increases air charge of ambient air drawn into the intake passage in order to provide greater charge density during combustion to increase power output and/or engine-operating efficiency. The turbocharger may include a compressor (not shown in FIG. 1) which is at least partially driven by a turbine (not shown in FIG. 1). While in this case a single turbocharger is included, the system may include multiple turbine and/or compressor stages. As shown in FIG. 1, the turbocharger is coupled to the engine and mounted on an integrated front end 102 (e.g., shelf) of the engine. The integrated front end provides various mounting bosses for support structures supporting various components of the engine, including the turbocharger. Due to the mounting of the turbocharger on the integrated front end of the engine, the turbocharger may experience a larger amount of vibrations than traditional turbocharger mounting configurations (e.g., where the turbocharger is bolted directly to the engine).

FIG. 1 shows a coordinate axis 122 including a vertical axis 124, a horizontal axis 126, and a lateral axis 128. The turbocharger has a vertical exhaust outlet 130, the vertical exhaust outlet positioned vertically (e.g., perpendicular) with respect to a longitudinal axis 132 of the engine. The longitudinal axis of the engine is aligned with the horizontal axis and the vertical exhaust outlet is aligned with the vertical axis. As such, a flow direction of exhaust through the vertical exhaust outlet is perpendicular to a flow direction of exhaust through the exhaust passage upstream of the turbocharger.

In some embodiments, the engine system may include an exhaust gas treatment system coupled in the exhaust passage upstream or downstream of the turbocharger. In one example embodiment having a diesel engine, the exhaust gas treatment system may include a diesel oxidation catalyst (DOC) and a diesel particulate filter (DPF). In other embodiments, the exhaust gas treatment system may additionally or alternatively include one or more emission control devices. Such emission control devices may include a selective catalytic reduction (SCR) catalyst, three-way catalyst, NO_(x) trap, as well as filters or other systems and devices.

A controller 148 may be employed to control various components related to the vehicle system. In one example, the controller includes a computer control system. The controller further includes computer readable storage media (not shown) including code for enabling on-board monitoring and control of rail vehicle operation. The controller, while overseeing control and management of the vehicle system, may receive signals from a variety of sensors 150 to determine operating parameters and operating conditions, and correspondingly adjust various engine actuators 152 to control operation of the vehicle. For example, the controller may receive signals from various engine sensors including, but not limited to, engine speed, engine load, boost pressure, exhaust pressure, ambient pressure, exhaust temperature, and the like. Correspondingly, the controller may control aspects and operations of the vehicle system by sending commands to various components such as traction motors, alternator, cylinder valves, throttle, and the like.

FIG. 2 illustrates an example muffler system 200 including a muffler 210 coupled to a turbocharger (such as turbocharger 120 of FIG. 1) via a vibration isolation device. The muffler system may be included as part of vehicle system 100 of FIG. 1. The turbocharger includes a turbine 202 and compressor 204. Exhaust gas from an engine, such as engine 104 of FIG. 1, enters the turbine via turbine inlet 206, impinges on the blades of a turbine rotor (not shown), causing the rotor to spin a shaft coupled to a rotor of the compressor, and exits the turbine via a turbine outlet 208.

The turbine outlet is fluidically coupled to muffler inlet 212. Exhaust gas from the turbine is passed to the muffler via the muffler inlet. The exhaust gas may pass through one or more chambers or other sound-reducing structures within the muffler before exiting the muffler via muffler outlet 214. The muffler outlet may be fluidically coupled to an exhaust passage, such as exhaust passage 116, in some examples.

The close coupling of the muffler and turbocharger may place a large amount of excitation forces on the muffler, as the thermal load and vibrations of the turbocharger are transmitted to the muffler. Further, the turbocharger mounting configuration, where the turbocharger is supported by the integrated front end of the engine, causes additional vibrations to be passed to the muffler. The excitation forces may result in degradation to the muffler, particularly at welded joints of the muffler. To address this, vibration isolators may be coupled between the turbine and the muffler. The types of vibration isolators that may be used, however, are limited due to the high heat environment and limited packaging space available. While a spring may be present to absorb vibrations and/or isolate the muffler from turbocharger vibrations, the spring's ability to isolate vibrations may be limited to a certain extent since theoretically a spring mass system will come to rest at an infinite time once the spring is displaced from its original position.

According to embodiments disclosed herein and elaborated with respect to FIGS. 2-3, a vibration isolation device 218 including a vibration dampening element and an active biasing element may be coupled between the turbocharger and muffler. When a load is applied on the active biasing element, it undergoes deformation and when the active biasing element is heated to a certain temperature, it regains its original predetermined shape. Thus, when the active biasing element is simultaneously heated at certain temperature and a load is placed on it, it will try to regain its original shape, producing internal forces which are in opposite direction of the applied force. This property may be used for vibration damping when used in combination with the vibration dampening element (e.g., a spring). Use of vibration dampening element along with an active biasing element can absorb and reduce the high frequency turbo excitations encountered by the muffler, which leads to improved life of weld joints and improved reliability for the muffler.

The vibration isolation device may be coupled between an outrigger plate of the turbocharger (illustrated as outrigger plate 222 of FIG. 3) and a base plate 216 of the muffler. Further, a bellow 220 and/or liner plate 221 (illustrated in FIG. 3) may be present to seal the fluid coupling between the turbine outlet and muffler inlet, in order to prevent leaks of exhaust gas, provide thermal insulation, direct the exhaust gas in a desired flow path, and/or additional functions. The bellow may be welded or otherwise coupled to the outrigger plate and muffler base plate, while the liner plate may be welded or otherwise coupled to the outrigger plate The turbine outlet, outrigger plate, and bellow may collectively form the vertical exhaust outlet 130 illustrated in FIG. 1. While two vibration isolation devices are illustrated in FIG. 2, it is to be understood that virtually any number of vibration isolation devices may be present in the muffler system.

FIG. 3 is a cross-sectional view 300 of the muffler system 200 of FIG. 2, including a more detailed view of the vibration isolation device. As shown in FIG. 3, the vibration isolation device includes a vibration dampening element 224 and an active biasing element 226. The vibration dampening element may be a spring. The spring may be a suitable spring, such as a leaf or coil spring, and/or the spring may comprise a helical, coiled material, such as spring steel, wound around the active biasing element and having a suitable spring force. In one example, the spring force may be selected based on k·x for the spring element, where k is stiffness of the spring; x is spring deflection and σ·A for the active biasing element, assuming a linear stress-strain assumption in the operating temperature range where σ is stress on the active biasing element and A is the area of cross section of the active biasing element. The active biasing may have a shear modulus in a range of 70-90 GPa and may be comprised of a wire having a diameter in a range of 8-15 mm. The wire may be wound into a coil having a suitable number of turns, such as in a range of 8-12 turns, resulting in a pitch in a range of 4-8 mm, for example. The active biasing element may have an overall diameter (e.g., coil diameter) in a range of 20-40 mm.

Thus, the active biasing element may be surrounded by the vibration dampening element and may be parallel to and aligned with a central axis 228 of the vibration dampening element. The central axis of the vibration dampening element may be aligned with the vertical axis of the coordinate system of FIG. 1. The vibration dampening element and active biasing element may each have a first end mechanically coupled to the outrigger plate of the turbocharger or other suitable turbine outlet structure. The vibration dampening element and active biasing element may each have a second, opposite end mechanically coupled to the base plate or other suitable structure of the muffler.

In one example, the active biasing element may be comprised of a suitable material, such as a bi-metallic structure or an alloy of nickel and titanium, an alloy of copper, aluminum, and nickel, iron-based alloys, or copper-based alloys. Each of the above-listed materials may have differing tensile strengths, heat tolerance, shape-regaining capabilities, etc., and as such a desired material may be selected based on application-specific parameters (e.g., how much force the material may be exposed to, the temperature of the environment in which the material is placed, etc.).

The active biasing element may be a one-way shape-memory alloy that “remembers” a shape such that following a deformation resulting from an applied force, the material can return to its original shape when heated above a transition temperature. In another example, the active biasing element may be a two-way shape-memory alloy that “remembers” two shapes, one at low temperatures, and one at temperatures above a transition temperature. The two-way shape memory alloy may be pre-stressed in some examples, such that the material assumes a desired shape capable of absorbing applied forces upon deformation, rather deforming to an undesired shape following application of force.

As described above, the active biasing element may be tuned to return to its original shape at a desired temperature, following deformation due to an applied force. The active biasing element may be heated from exhaust gas passing through the turbocharger and muffler. The active biasing element may be tuned to a suitable temperature, such as 100° C., 50° C., 30° C., or other suitable temperature, depending on the vibration isolation demands of the system. In one example, the active biasing element may be tuned to regain its original shape following deformation when the active biasing element is heated to room temperature (e.g., 20° C.). In another example, the active biasing element may have an activation (e.g., transition) temperature in a range of 9-49° C. The tuned temperature of the active biasing element is dependent on the relative ratio of the metals comprising the alloy of the wire. In one example, the active biasing element may include a ratio of nickel to titanium of 50% nickel to 50% titanium, although other ratios are possible. The active biasing element may have a shear modulus in a range of 60-75 GPa when in a hyper-elastic stage. The active biasing element may comprise a wire, and the wire may have a suitable thickness, such as less than 10 mm. In one example, the diameter may be in the range of 2-6 mm. The thickness of the wire may vary per weight of the muffler, magnitude of excitations and amount of damping to be provided, for example. The wire may have a suitable length, such as in a range of 65-80 mm. The vibration isolation device may be comprised of more than one vibration dampening element-active biasing element pair. For example, the vibration isolation device may be comprised of 10-20 vibration dampening element-active biasing element pairs, which may be spaced together in one or more clusters or may be evenly dispersed along the interface between the turbocharger and muffler.

In one example, a vibration isolation device comprises a vibration dampening element wound around an active biasing element. The vibration dampening element may comprise a steel spring having a shear modulus of 80 GPa. A diameter of the wire comprising the spring may be 12 mm. The spring may be comprised of ten turns and have a coil diameter of 30 mm, with a pitch of the spring being 6 mm. The active biasing element may be comprised of a wire having a composition of 50% nickel and 50% titanium with a diameter of 4 mm and length of 72 mm. The modulus of the wire in a hyper-elastic stage may be 67 GPa. The vibration isolation device may be comprised 16 vibration dampening element-active biasing element pairs. Together, these parameters may provide for a vibration isolation device that attenuates transfer of vibrations from the turbocharger to the muffler when the muffler and turbocharger are sized and positioned for use in a large engine system, such as that of a locomotive.

The muffler may include an outer liner 232 surrounding an inner liner 230, with an air gap between the outer liner and the inner liner. The outer liner may be coupled to the base plate of the muffler. The inner liner may also be coupled to the base plate of the muffler, via one or more standoffs in some examples. Both the outer liner and inner liner may be coupled to a top lid 234 of the muffler.

The inner and outer liner may each undergo deformation during operation of the engine and turbocharger, producing stress in weld areas, which leads to weld joint failures in weld joints between outer liner-base plate, inner liner-standoff bottom plate, outer liner-top lid, etc. As illustrated in FIG. 3, the inner liner and outer liner may be coupled via one or more active biasing elements 236. The active biasing elements coupled between the inner and outer liner may be positioned at high deflection points, such as at the center of the muffler, e.g., aligned along or arranged across longitudinal axis 238 of the muffler. The longitudinal axis of the muffler may be aligned with the horizontal axis of the coordinate system illustrated in FIG. 1. Such an arrangement reduces relative movement of the inner and outer liners and makes the muffler stiffer. Other mechanisms for strengthening the muffler, such as ribs between the inner and outer liner, may increase muffler weight. Active biasing elements, on the other hand, are very light in weight and thus adding active biasing elements for increasing the muffler stiffness does not increase the weight of the muffler. Here, the active biasing elements may be in hyper-elastic form and may be heated by exhaust gases. When the inner and outer liner start to move away from each other, the forces will deform the active biasing elements. Since the active biasing elements are in hyper-elastic form, each element will try to regain its initial unreformed shape, producing forces in the opposite direction, minimizing deformations and producing damping. This described arrangement makes the muffler stiffer and may reduce weld failures in the muffler.

The composition of the active biasing elements coupling the inner and outer liner may be similar to the composition of the active biasing element of the vibration isolation device coupling the muffler to the turbocharger, as described above. In other examples, the active biasing elements between the inner and outer liner may have a different composition and/or thickness.

Thus, as explained above, an active biasing element may be present to dampen vibrations passed from one engine component to another, such as from a turbocharger to a muffler. The active biasing element may be tuned to regain an original shape following a deformation and exposure to temperature above a transition temperature. As such, at relatively low temperatures (e.g., temperatures below the transition temperature), the active biasing element may couple the two engine components together according to a first shape, and then if a force is applied to the active biasing element (e.g., if the turbocharger vibrates or otherwise moves), the active biasing element may couple the two engine components together in a second, deformed shape. For example, the active biasing element may bend, contract, or otherwise deform, in a direction of the applied force. Then, once the temperature of the active biasing element reaches the transition temperature, the active biasing element may couple the two engine components together in the original shape. In this way, when the active biasing element temperature is relatively low (due to low exhaust temperature, or due to the engine not being in operation, for example), the active biasing element may allow more vibrations to be passed from one engine component to another (e.g., more vibrations may be passed from the turbocharger to the muffler). When the active biasing element temperature is relatively high (due to higher exhaust temperature resulting from engine operation, engine operation at an increased load and/or engine speed, etc.), fewer vibrations may be passed from the one engine component to another. The transition temperature may be a function of the relative proportions of the various materials comprising the active biasing element.

In another example, the active biasing element may be configured such that when the temperature of the active biasing element is relatively high (e.g., above the transition temperature), more vibrations are passed from one component to another, and when the temperature of the active biasing element is relatively low, fewer vibrations are passed from one component to another. In a further example, if the temperature of the active biasing element is higher than a second threshold temperature, greater than the transition temperature, the elasticity of the active biasing element may be reduced or completely eliminated, so that the active biasing element acts as more of a rigid brace coupling the two engine components. Additionally, in some examples, a seal or other coupling mechanism may become active during certain conditions, in order to avoid damage to the engine components (e.g., muffler) when the active biasing element experiences slack.

As explained above, the shape regaining capabilities of the active biasing element is dependent on the temperature of the active biasing element. When the active biasing element couples two engine exhaust components together, such as when the active biasing element is coupled between the turbocharger and muffler, the shape memory functionality of the active biasing element depends on engine temperature. Thus, in some examples, a controller (such as controller 148 of FIG. 1) may be configured to respond to vibration levels of the engine and/or turbocharger, and adjust exhaust temperature accordingly, to ensure the active biasing element is capable of dampening vibrations. This may include purposely increasing exhaust temperature, by adjusting fuel injection parameters, EGR rate, engine load (by adjusting a notch throttle setting, for example), engine speed, or other parameters.

While the above-described active biasing element and vibration isolation device is described with respect to dampening vibrations passed from a turbocharger to a muffler, other configurations are possible. For example, the vibration isolation device described herein may be coupled between the turbine housing and compressor housing of the turbocharger, coupled between the turbocharger and the engine and/or platform on which the turbocharger is mounted, coupled at a pipe or conduit joint, or other location subject to vibration.

An embodiment relates to a system comprising an exhaust component, a muffler configured to receive exhaust gas from the exhaust component, and a vibration isolation device coupled between the exhaust component and the muffler, the vibration isolation device comprising a vibration dampening element and an active biasing element. In an example, the vibration dampening element comprises a spring, and the active biasing element is positioned within the spring, e.g., along a central axis of the spring.

The active biasing element may be comprised of a one-way shape-memory alloy. The alloy may be comprised of nickel and titanium in one example, or may be a bi-metallic structure in another example. The active biasing element may be tuned to regain its original structure at a temperature of 20° C. or greater.

In one example, the exhaust component comprises a turbocharger. In other examples, the exhaust component may include an engine, an aftertreatment device, or other suitable component configured to expel exhaust gas. The vibration isolation device may be coupled between an outrigger plate of an exhaust outlet of a turbine of the turbocharger and a base plate of an exhaust inlet of the muffler. The vibration isolation device may be a first vibration isolation device, and the system may further comprise a second vibration isolation device also coupled between the outrigger plate and the base plate. The one or more vibration isolation devices may create a gap between the outrigger plate and the base plate. To seal the gap and prevent leakage of exhaust gas, the system may further comprise one or more of a bellow and liner plate coupled to the outrigger plate, the one or more of the bellow and liner plate configured to seal an exhaust gas stream between the turbine of the turbocharger and the muffler.

In an example, the active biasing element is a first active biasing element. The muffler may comprise an inner liner, an outer liner, and at least one additional active biasing element coupled between the inner liner and the outer liner.

Another embodiment relates to a muffler. The muffler comprises an outer liner, an inner liner positioned within the outer liner and configured to receive exhaust gas, and at least one active biasing element coupled between the outer liner and the inner liner.

The at least one active biasing element may be positioned along a longitudinal axis of the muffler. The at least one shape-memory alloy wire may comprise 50% nickel and 50% titanium.

The outer liner may be coupled to a base plate of the muffler at a first end and a top lid of the muffler at a second end. The inner liner may be coupled to a stand-off of the base plate of the muffler at a first end and the top lid at a second end. The active biasing element may act as a brace, and the active biasing element may clamp the inner and outer liners more tightly at exhaust gas temperatures above a threshold temperature relative to how tightly the active biasing element may clamp the inner and outer liners at exhaust gas temperatures below the threshold.

In an example, the base plate of the muffler is coupled to a turbocharger, and the exhaust gas is received from the turbocharger. The base plate of the muffler may be coupled to the turbocharger via one or more vibration isolation devices, the one or more vibration isolation devices each comprising a respective vibration dampening element and a respective active biasing element.

In an embodiment, a system comprises a turbocharger, a muffler configured to receive exhaust gas from the turbocharger, and a vibration isolation device coupled between the turbocharger and the muffler. The muffler comprises an outer liner, an inner liner positioned within the outer liner, and at least one first active biasing element coupled between the outer liner and the inner liner. The vibration isolation device comprises a vibration dampening element and a second active biasing element. The second active biasing element may be responsive to a threshold temperature to return to a determined shape or configuration, and the system may further comprise a controller configured to increase an exhaust gas temperature to the threshold temperature or greater in response to a vibration level of the turbocharger exceeding a vibration level threshold.

The system further comprises an engine to pass exhaust gas to the turbocharger, where the engine, turbocharger, and muffler are installed in a vehicle.

As used herein, an element or step recited in the singular and proceeded with the word “a” or “an” should be understood as not excluding plural of said elements or steps, unless such exclusion is explicitly stated. Furthermore, references to “one embodiment” of the present invention are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. Moreover, unless explicitly stated to the contrary, embodiments “comprising,” “including,” or “having” an element or a plurality of elements having a particular property may include additional such elements not having that property. The terms “including” and “in which” are used as the plain-language equivalents of the respective terms “comprising” and “wherein.” Moreover, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements or a particular positional order on their objects.

This written description uses examples to disclose the invention, including the best mode, and also to enable a person of ordinary skill in the relevant art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those of ordinary skill in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims. 

1. A system, comprising: an exhaust component; a muffler configured to receive exhaust gas from the exhaust component; and a vibration isolation device coupled between the exhaust component and the muffler, the vibration isolation device comprising a vibration dampening element and an active biasing element.
 2. The system of claim 1, wherein the vibration dampening element comprises a spring, and wherein active biasing element is coupled to the spring.
 3. The system of claim 1, wherein the active biasing element comprises a bi-metallic structure.
 4. The system of claim 1, wherein the active biasing element comprises a one-way shape-memory alloy.
 5. The system of claim 4, wherein the alloy comprises nickel and titanium.
 6. The system of claim 1, wherein the active biasing element is responsive to a temperature of 20 degrees Celsius or greater to return to a determined shape or configuration.
 7. The system of claim 1, wherein the exhaust component is coupled to a turbocharger.
 8. The system of claim 7, wherein the vibration isolation device is coupled between an outrigger plate of an exhaust outlet of a turbine of the turbocharger and a base plate of an exhaust inlet of the muffler.
 9. The system of claim 8, wherein the vibration isolation device is a first vibration isolation device, and further comprising a second vibration isolation device that is coupled between the outrigger plate and the base plate.
 10. The system of claim 8, further comprising one or more of bellow and liner plate coupled to the outrigger plate, the one or more of the bellow and liner plate configured to seal an exhaust gas stream between the turbine of the turbocharger and the muffler.
 11. The system of claim 1, wherein the active biasing element is a first active biasing element, and wherein the muffler comprises an inner liner, an outer liner, and at least one additional active biasing element coupled between the inner liner and the outer liner.
 12. A muffler, comprising: an outer liner; an inner liner positioned within the outer liner and configured to receive exhaust gas; and at least one active biasing element coupled between the outer liner and the inner liner.
 13. The muffler of claim 12, wherein the at least one active biasing element is positioned along a longitudinal axis of the muffler.
 14. The muffler of claim 12, wherein the at least one active biasing element comprises a brace.
 15. The muffler of claim 12, wherein the active biasing element clamps the inner and outer liners more tightly at exhaust gas temperatures above a threshold temperature.
 16. The muffler of claim 12, wherein the outer liner is coupled to a base plate of the muffler at a first end and a top lid of the muffler at a second end, and wherein the inner liner is coupled to a stand-off of the base plate of the muffler at a first end and the top lid at a second end.
 17. The muffler of claim 16, wherein the base plate of the muffler is coupled to a turbocharger, the exhaust gas received from the turbocharger.
 18. The muffler of claim 17, wherein the base plate of the muffler is coupled to the turbocharger via one or more vibration isolation devices, the one or more vibration isolation devices each comprising a respective vibration dampening element and a respective active biasing element.
 19. A system, comprising: a turbocharger; a muffler configured to receive exhaust gas from the turbocharger, the muffler comprising an outer liner, an inner liner positioned within the outer liner, and at least one first active biasing element coupled between the outer liner and the inner liner; and a vibration isolation device coupled between the turbocharger and the muffler, the vibration isolation device comprising a vibration dampening element and a second active biasing element.
 20. The system of claim 19, wherein the second active biasing element is responsive to a threshold temperature to return to a determined shape or configuration, and further comprising a controller configured to increase an exhaust gas temperature to the threshold temperature or greater in response to a vibration level of the turbocharger exceeding a vibration level threshold. 